The invention relates to a connection arrangement for a mineral-insulated conduit to at least one tube-shaped structure, wherein at least one end of the two ends of the mineral-insulated conduit is arranged partially overlapping with a tube-shaped structure and is affixed by welding or soldering.
Connection arrangements of this type are known, in particular for sensors in the sector of exhaust gas conduction of a motor vehicle.
WO 95/18965 describes a measuring probe with a metallic housing and a sensor chip arranged in it, which has a sensor element. The sensor chip is connected to the electrical conductors of a mineral-insulated metal sheathed cable. The housing is connected to the metal sheathed cable via a jack, which is set on the metal sheathed conduit and is bonded to it by laser welding. The housing and the jack are likewise bonded by laser welding.
In order to produce the laser weld connections between the metal sheathed cable and the jack, as well as between the jack and housing, the respective parts to be connected must be adapted to each other in diameter. Such an adaptation is necessary in order to prevent air gaps between the parts, which generally makes the laser welding difficult. In addition, the weld connection constructed in this manner is susceptible to vibrations, which play a large role especially in motor vehicles. A break in the weld connection leads to a high mechanical stress on the electrical connection to the sensor chip and can lead to a failure of the sensor.
The problem results of making available a connection arrangement for a mineral-insulated conduit to a tube-shaped structure, which is simple to produce and which avoids the disadvantages of the prior art.
The problem is solved in that a sheath surface in the region of the overlap has a raised structure, and the end of the mineral-insulated conduit and the tube-shaped structure contact each other on all sides in the region of the overlap, wherein the contact surface is smaller than the sheath surface.
A simple connection arrangement results with exceptional mechanical rigidity and high resistance against vibrations, which is especially excellently suited for a use according to the invention on sensors, which are installed in or on motor vehicles. On account of the structured sheath surface, in addition, a low heat conduction is to be established in the region of the connection arrangement. Thus, for example, using the connection arrangement, a sensor can be contacted, for use in hot gases, with a very short-dimensioned mineral-insulated conduit, which forms the transition to a connection sheath and a cable that can be only slightly thermally loaded, for example a cable with a plastic casing. A short connection constructed in this manner between the sensor and the cable is especially advantageous when only small installation dimensions are available, as is customary in a motor vehicle.
It is especially advantageous if the end of the mineral-insulated conduit is plugged into the tube-shaped structure. The tube-shaped structure can, for example, be a sensor housing or a connection sleeve for a flexible cable.
It has been proven worthwhile if the structured sheath surface is formed from the outer peripheral surface of the end of the mineral-insulated conduit. It is also possible, however, that the structured sheath surface be formed from the inner peripheral surface of the tube-shaped structure.
The structuring of the sheath surface herein can be made from a fluting. Suitable types of flutings include, for example, longitudinal flutings, transverse flutings, or point-flutings. However, a fluting which is constructed in a manner similar to a threading or as a diagonal fluting can also be used.
As a structure for a sheath surface, a wire or a wire mesh is suitable, which can be affixed.
According to an overlapping arrangement of a tube-shaped structure with a mineral-insulated conduit, wherein the structured sheath surface is arranged in the region of the overlap, the external periphery of the tube-shaped structure is reduced. Here, the structured sheath surface is deformed, and a form-fitting connection is produced between the tube-shaped structure and the mineral-insulated conduit. The parts thus fitted to each other are then additionally bonded by a laser welding.